#ifndef TEMPFILE_H
#define TEMPFILE_H
+#include "list.h"
+
/*
* Handle temporary files.
*
*
* The caller:
*
- * * Allocates a `struct tempfile` either as a static variable or on
- * the heap, initialized to zeros. Once you use the structure to
- * call `create_tempfile()`, it belongs to the tempfile subsystem
- * and its storage must remain valid throughout the life of the
- * program (i.e. you cannot use an on-stack variable to hold this
- * structure).
- *
* * Attempts to create a temporary file by calling
- * `create_tempfile()`.
+ * `create_tempfile()`. The resources used for the temporary file are
+ * managed by the tempfile API.
*
* * Writes new content to the file by either:
*
- * * writing to the file descriptor returned by `create_tempfile()`
- * (also available via `tempfile->fd`).
+ * * writing to the `tempfile->fd` file descriptor
*
* * calling `fdopen_tempfile()` to get a `FILE` pointer for the
* open file and writing to the file using stdio.
*
+ * Note that the file descriptor created by create_tempfile()
+ * is marked O_CLOEXEC, so the new contents must be written by
+ * the current process, not any spawned one.
+ *
* When finished writing, the caller can:
*
* * Close the file descriptor and remove the temporary file by
* control of the file.
*
* * Close the file descriptor without removing or renaming the
- * temporary file by calling `close_tempfile()`, and later call
+ * temporary file by calling `close_tempfile_gently()`, and later call
* `delete_tempfile()` or `rename_tempfile()`.
*
- * Even after the temporary file is renamed or deleted, the `tempfile`
- * object must not be freed or altered by the caller. However, it may
- * be reused; just pass it to another call of `create_tempfile()`.
+ * After the temporary file is renamed or deleted, the `tempfile`
+ * object is no longer valid and should not be reused.
*
* If the program exits before `rename_tempfile()` or
* `delete_tempfile()` is called, an `atexit(3)` handler will close
* and remove the temporary file.
*
* If you need to close the file descriptor yourself, do so by calling
- * `close_tempfile()`. You should never call `close(2)` or `fclose(3)`
+ * `close_tempfile_gently()`. You should never call `close(2)` or `fclose(3)`
* yourself, otherwise the `struct tempfile` structure would still
* think that the file descriptor needs to be closed, and a later
* cleanup would result in duplicate calls to `close(2)`. Worse yet,
* Error handling
* --------------
*
- * `create_tempfile()` returns a file descriptor on success or -1 on
- * failure. On errors, `errno` describes the reason for failure.
+ * `create_tempfile()` returns an allocated tempfile on success or NULL
+ * on failure. On errors, `errno` describes the reason for failure.
*
- * `delete_tempfile()`, `rename_tempfile()`, and `close_tempfile()`
- * return 0 on success. On failure they set `errno` appropriately, do
- * their best to delete the temporary file, and return -1.
+ * `rename_tempfile()` and `close_tempfile_gently()` return 0 on success.
+ * On failure they set `errno` appropriately and return -1.
+ * `delete_tempfile()` and `rename` (but not `close`) do their best to
+ * delete the temporary file before returning.
*/
struct tempfile {
- struct tempfile *volatile next;
+ volatile struct volatile_list_head list;
volatile sig_atomic_t active;
volatile int fd;
FILE *volatile fp;
volatile pid_t owner;
- char on_list;
struct strbuf filename;
};
/*
* Attempt to create a temporary file at the specified `path`. Return
- * a file descriptor for writing to it, or -1 on error. It is an error
- * if a file already exists at that path.
+ * a tempfile (whose "fd" member can be used for writing to it), or
+ * NULL on error. It is an error if a file already exists at that path.
+ */
+extern struct tempfile *create_tempfile(const char *path);
+
+/*
+ * Register an existing file as a tempfile, meaning that it will be
+ * deleted when the program exits. The tempfile is considered closed,
+ * but it can be worked with like any other closed tempfile (for
+ * example, it can be opened using reopen_tempfile()).
+ */
+extern struct tempfile *register_tempfile(const char *path);
+
+
+/*
+ * mks_tempfile functions
+ *
+ * The following functions attempt to create and open temporary files
+ * with names derived automatically from a template, in the manner of
+ * mkstemps(), and arrange for them to be deleted if the program ends
+ * before they are deleted explicitly. There is a whole family of such
+ * functions, named according to the following pattern:
+ *
+ * x?mks_tempfile_t?s?m?()
+ *
+ * The optional letters have the following meanings:
+ *
+ * x - die if the temporary file cannot be created.
+ *
+ * t - create the temporary file under $TMPDIR (as opposed to
+ * relative to the current directory). When these variants are
+ * used, template should be the pattern for the filename alone,
+ * without a path.
+ *
+ * s - template includes a suffix that is suffixlen characters long.
+ *
+ * m - the temporary file should be created with the specified mode
+ * (otherwise, the mode is set to 0600).
+ *
+ * None of these functions modify template. If the caller wants to
+ * know the (absolute) path of the file that was created, it can be
+ * read from tempfile->filename.
+ *
+ * On success, the functions return a tempfile whose "fd" member is open
+ * for writing the temporary file. On errors, they return NULL and set
+ * errno appropriately (except for the "x" variants, which die() on
+ * errors).
*/
-extern int create_tempfile(struct tempfile *tempfile, const char *path);
+
+/* See "mks_tempfile functions" above. */
+extern struct tempfile *mks_tempfile_sm(const char *filename_template,
+ int suffixlen, int mode);
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile_s(const char *filename_template,
+ int suffixlen)
+{
+ return mks_tempfile_sm(filename_template, suffixlen, 0600);
+}
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile_m(const char *filename_template, int mode)
+{
+ return mks_tempfile_sm(filename_template, 0, mode);
+}
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile(const char *filename_template)
+{
+ return mks_tempfile_sm(filename_template, 0, 0600);
+}
+
+/* See "mks_tempfile functions" above. */
+extern struct tempfile *mks_tempfile_tsm(const char *filename_template,
+ int suffixlen, int mode);
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile_ts(const char *filename_template,
+ int suffixlen)
+{
+ return mks_tempfile_tsm(filename_template, suffixlen, 0600);
+}
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile_tm(const char *filename_template, int mode)
+{
+ return mks_tempfile_tsm(filename_template, 0, mode);
+}
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *mks_tempfile_t(const char *filename_template)
+{
+ return mks_tempfile_tsm(filename_template, 0, 0600);
+}
+
+/* See "mks_tempfile functions" above. */
+extern struct tempfile *xmks_tempfile_m(const char *filename_template, int mode);
+
+/* See "mks_tempfile functions" above. */
+static inline struct tempfile *xmks_tempfile(const char *filename_template)
+{
+ return xmks_tempfile_m(filename_template, 0600);
+}
/*
* Associate a stdio stream with the temporary file (which must still
* be open). Return `NULL` (*without* deleting the file) on error. The
- * stream is closed automatically when `close_tempfile()` is called or
+ * stream is closed automatically when `close_tempfile_gently()` is called or
* when the file is deleted or renamed.
*/
extern FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode);
static inline int is_tempfile_active(struct tempfile *tempfile)
{
- return tempfile->active;
+ return tempfile && tempfile->active;
}
/*
* If the temporary file is still open, close it (and the file pointer
* too, if it has been opened using `fdopen_tempfile()`) without
* deleting the file. Return 0 upon success. On failure to `close(2)`,
- * return a negative value and delete the file. Usually
- * `delete_tempfile()` or `rename_tempfile()` should eventually be
- * called if `close_tempfile()` succeeds.
+ * return a negative value. Usually `delete_tempfile()` or `rename_tempfile()`
+ * should eventually be called regardless of whether `close_tempfile_gently()`
+ * succeeds.
*/
-extern int close_tempfile(struct tempfile *tempfile);
+extern int close_tempfile_gently(struct tempfile *tempfile);
/*
* Re-open a temporary file that has been closed using
- * `close_tempfile()` but not yet deleted or renamed. This can be used
+ * `close_tempfile_gently()` but not yet deleted or renamed. This can be used
* to implement a sequence of operations like the following:
*
* * Create temporary file.
*
- * * Write new contents to file, then `close_tempfile()` to cause the
+ * * Write new contents to file, then `close_tempfile_gently()` to cause the
* contents to be written to disk.
*
* * Pass the name of the temporary file to another program to allow
* `delete_tempfile()` for a `tempfile` object that has already been
* deleted or renamed.
*/
-extern void delete_tempfile(struct tempfile *tempfile);
+extern void delete_tempfile(struct tempfile **tempfile_p);
/*
* Close the file descriptor and/or file pointer if they are still
* `rename(2)`. It is a bug to call `rename_tempfile()` for a
* `tempfile` object that is not currently active.
*/
-extern int rename_tempfile(struct tempfile *tempfile, const char *path);
+extern int rename_tempfile(struct tempfile **tempfile_p, const char *path);
#endif /* TEMPFILE_H */